Normobaric Oxygen Therapy for Individuals With First-Episode Psychosis

* Diagnosis of a schizophrenia-spectrum disorder or mood disorder with psychotic features as determined using the Structured Clinical Interview for the DSM-5. * Less than 5 years since the onset of frank psychotic symptoms as determined using the Symptom Onset in Schizophrenia Inventory . * No evidence of a pre-existing intellectual disability defined as a premorbid IQ \>70 as estimated using the Reading subtest of the Wide Range Achievement Test-4. * Ages 15-35 * Non-smoker for past six months * Absence of suicidal ideation or behavior over the past month as assessed by the Columbia Suicide Severity Rating Scale * The American Association for Respiratory Care notes that "no absolute contraindications to oxygen therapy exist when indications \[for oxygen therapy\] are present."